Static Friction Compensation for Enhancing Motor Control Precision

Most of existing friction compensation techniques are based on friction models that uses the velocity as its input. These methods are difficult to apply to inexpensive encoder-based actuator systems that do not exhibit sufficiently large presliding displacement. This paper presents a new method of friction compensation that can be applied to geared actuators with high presliding stiffness. The compensator consists of three components that compensate: (a) static friction, (b) rate-dependent kinetic friction, and (c) dynamic friction involving presliding viscoelasticity. The first component employs dither-like torque command, and the other two are based on friction models involving precalibrated parameters. The proposed method is validated through experiments employing a harmonic drive transmission. In particular, it is suggested that the dither-like static friction compensation and the viscosity in the presliding model significantly improve the performance of the compensator.

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Low-cost backdrivable motor control based on feed-forward/feed-back friction compensation

2015 IEEE International Conference on Robotics and Automation (ICRA) ◽

10.1109/icra.2015.7139898 ◽

2015 ◽

Cited By ~ 4

Author(s):

S. Ishikawa ◽

M. Nishio ◽

T. Sugihara

Keyword(s):

Motor Control ◽

Low Cost ◽

Friction Compensation ◽

Feed Forward

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Research on Theodolite Auto-Focus Motor Control Technology Based on a Disturbance Observer

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.415.250 ◽

2013 ◽

Vol 415 ◽

pp. 250-255

Author(s):

Chun Tong Liu ◽

Yang Zhang ◽

Zhen Xin He ◽

Bing Li

Keyword(s):

Motor Control ◽

Trajectory Planning ◽

Disturbance Observer ◽

Control Method ◽

Servo Control ◽

Control Precision ◽

Servo Control System ◽

Dc Motor Control ◽

Integral Separation ◽

Auto Focusing

The design of DC servo control system for focus motor is an important part to realize the electronic theodolites auto-focusing. Focus motor is seriously influenced by various disturbances, such as friction and torque fluctuation, in frequently reversing process. It is difficult to accurately locate. To solve these problems, a DC motor control method was put forward which combined the integral separation PID and disturbance observer. Based on the three closed-loop DC servo system, the integral separation PID controller was taken in position loop, in order to eliminate static error and improve the control precision. The methods of motor trajectory planning were analyzed, the 4-5-6-7 interpolation trajectory planning was used to decline or prevent the start-stop impact and oscillation. The effectiveness of the control strategy was verified by comparative simulation experiment. The robustness anti-disturbance and location precision performance is improved significantly.

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Friction compensation control of an electropneumatic servovalve by using an evolutionary algorithm

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1243/0959651001540546 ◽

2000 ◽

Vol 214 (3) ◽

pp. 173-184 ◽

Cited By ~ 4

Author(s):

S H Choi ◽

C O Lee ◽

H S Cho

Keyword(s):

Search Algorithm ◽

Static Friction ◽

Open Loop ◽

Friction Model ◽

Experimental Results ◽

Friction Compensation ◽

Stick Slip ◽

Air Contamination ◽

Compensation Control ◽

Friction Models

A poppet-type electropneumatic servovalve developed in this study utilizes a poppet directly operated by a moving-coil actuator in the metering stage and is controlled by a digital controller. This servovalve is insensitive to air contamination and has no problem of air leakage at null, but it has relatively large friction between the O-rings installed in the peripheral grooves of the balance pistons and the valve sleeve. For friction compensation control, a static friction model that enables simulation of the stick-slip phenomena and a dynamic model that captures the friction behaviour such as presliding displacement and varying break-away force are presented. The parameters for the friction models are identified by utilizing an evolution strategy, one of the evolutionary algorithms, which is a probabilistic global search algorithm based on the model of natural evolution. These friction models are then used in designing a non-linear friction compensation controller. It is found in the experiment that the electropneumatic servovalve has almost no hysteresis and that the friction compensation control significantly improves valve performance. The experimental results of the open loop test on poppet positioning agree well with simulation results of the valve model with identified friction parameters. It is also shown that the experimental results of friction compensation control using a static friction model show a small steady state error but those using a dynamic friction model show almost no such error.

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Neuro-Adaptive Friction Compensation for Single-Link Flexible Robots Using Serial-Gray-Box Modeling Strategy

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2192838 ◽

2005 ◽

Vol 128 (2) ◽

pp. 297-306 ◽

Cited By ~ 1

Author(s):

Ali Bazaei ◽

Vahid Johari Majd

Keyword(s):

Control Method ◽

Static Friction ◽

Black Box ◽

Friction Compensation ◽

Friction Characteristic ◽

Flexible Mode ◽

The Neural Network ◽

Box Method ◽

Spring Coefficient ◽

Modeling Strategy

In this paper a previously offered black-box filtered-error neural-approximation-based control method for singularly perturbed flexible-link arms (FLA) is extended to a serial-gray-box method that assumes only the friction torques as unknown functions. Unlike the former method the knowledge of the unknown part is not used in design implementation of the fast control component. Because the neural network weights are updated adaptively the gray-box friction compensation method is applicable even when the friction functions change with time. Moreover, due to incorporation of the available first-principles knowledge into the control law the method exhibits dimensional extrapolation property with respect to nonfrictional measurable parameters of the plant. The capability of the gray-box method in the presence of static friction unmodeled dynamics are examined. Simulation results show that the proposed gray-box-based method provides better control modeling performances with less number of integrators in comparison with the black-box-based method. A procedure for determination of the parameters of the distributed mass-spring model is offered closed-form exact solutions for the equivalent deflection angle the spring coefficient the slope of the flexible-mode friction characteristic are derived. The gray-box method also works better than a newly developed Lyapunov-type controller which can be regarded as a robust control schema.

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The Design and Realization of Digital Controlled Frequency-Variable Speed-Adjustable System Based on DSP and SVPWM

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.308-310.2187 ◽

2011 ◽

Vol 308-310 ◽

pp. 2187-2190

Author(s):

Yan She ◽

Cai Ping Qu

Keyword(s):

Motor Control ◽

Real Time ◽

Digital Signal Processor ◽

Digital Signal ◽

Field Oriented Control ◽

Variable Speed ◽

Output Current ◽

Voltage Space Vector ◽

Current Harmonics ◽

Control Precision

The paper introduces voltage space vector pulse wide modulation (SVPWM) arithmetic and the field oriented control (FOC), develops a suit of Digital Controlled frequency-variable speed-adjustable system based on digital signal processor (DSP) TMS320LF2407 of TI company For motor control, and research and analyze design parts of the system, presents the instantiation application result. The experimental results indicate: the laboratorial setting has a simpler hardware construction, less output current harmonics distortion, higher control precision and stronger real-time sigal processing.

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